Method, apparatus, and system for optimizing exhaust backpressure of internal combustion engine

ABSTRACT

A method for optimizing exhaust backpressure of an internal combustion engine, comprising the following steps: 1) arranging a damping component in an exhaust passage of the internal combustion engine, and allowing an exhaust discharged by the internal combustion engine to pass through the damping component; and 2) allowing the exhaust to be cooled prior to passing through the damping component, or allowing the exhaust to be cooled while passing through the damping component. The method allows for relatively high exhaust backpressure when the internal combustion engine has a low load, and for preventing the exhaust pressure from rising excessively rapid when the internal combustion engine has a heavy load. The apparatus and system for optimizing exhaust backpressure of an internal combustion engine is also provided.

FIELD OF THE INVENTION

The present invention pertains to the technical field of efficiencyenhancing of an internal combustion engine, and relates to a method foroptimizing exhaust backpressure of an internal combustion engine. Thepresent invention further relates to an apparatus and system foroptimizing exhaust backpressure of an internal combustion engine.

DESCRIPTION OF THE PRIOR ART

In this century, the world's oil resources insufficiency andenvironmental pollution problems have become increasingly prominent, andthere is the need to further improve the economy of the internalcombustion engine and exhaust cleaning. The energy efficiency of theinternal combustion engine, i.e. fuel efficiency also needs to befurther improved, which is the basis and prerequisite of all facilitiesand equipment powered by internal combustion engines to enhance energyefficiency.

At present, the main way to increase the energy efficiency of internalcombustion engine is to improve the ventilation effect, i.e. intake andexhaust process, of the internal combustion engine. The way of improvingintake is ‘pressure boost’, i.e. to increase the intake pressure; theway of improving exhaust is ‘depressurization’, i.e. to reduce theexhaust backpressure, that is, to reduce the resistance of the exhaust.‘Pressure boost’ and ‘depressurization’, the two complement each other.

The pressure boost technology developed at the beginning of last centurydramatically improves the performances of the power, economy andemission of the internal combustion engine, which has become animportant symbol of the internal combustion engine development. Pressureboost model has become the basic model of the internal combustionengine, and in particular, the turbine pressure boost technology thatuses the internal combustion engine exhaust gas to drive a turbine, andthen a compressor is driven by a turbine to ‘pressure boost’ intake airof an internal combustion engine, and the intercooling technology thatis combined with intake air pressure boost, have now developed into anear-perfect and are widely used. But the disadvantage is: theacceleration performance of the internal combustion engine is limiteddue to the internal combustion engine being sensitive to exhaustbackpressure.

The so-called ‘depressurization’ is to reduce the exhaust backpressure,and the exhaust backpressure is related to the exhaust resistance of theinternal combustion engine. With the increase of the load when theengine operates, the mass of the exhaust gas and the temperature of theexhaust gas are also increased. With the double impact of the mass andtemperature of the exhaust gas, the volume flow and the flow rate of theexhaust increase even larger, so that the resistance of the exhaustpassage, including the resistance of the other components (e.g., amuffler) in the exhaust passage, rises rapidly due to the law ofpositive pressure being proportional to the square of flow rate.Therefore, the internal combustion engine backpressure also increasesrapidly with the engine load. High backpressure means that the exhaustgas flow is encountered with a large resistance, such that the exhaustwithin the cylinder is difficult to discharge cleanly, thus affectingsubsequent combustion quality. Therefore, the exhaust backpressureaffects the performance of an internal combustion engine. The increaseof the backpressure will lead to decrease of the combustion efficiency,economy and emission performance of the internal combustion engine, andin the meantime the power performance decreases and fuel consumptionincreases. Data shows that this will cause at least more than 10% lossof energy efficiency to the internal combustion engine. Especially for aturbocharged internal combustion engine rotating at high speed relyingon an exhaust gas driven turbine, the increase of the exhaustbackpressure leads to a decrease of the pressure drop of the exhaust gaswhich drives the turbine, causing a decrease of the effect ofturbocharging, which in turn makes the intake pressure reduced, so as toresult in a further decrease of the energy efficiency of the internalcombustion engine. What is even more serious is that, with countriesbeing increasingly strict on international environmental regulations,the requirements for the internal combustion engine exhaust gastreatment are also increasingly higher.

As the backpressure of a system is the sum of the pressure drops formedby the airflow sequentially passes through each of the elements in thesystem, and the pressure drop formed by passing through each element isproportional to the square of the flow rate of the airflow passingthrough. Accordingly, after the installation of the exhaust processingdevices and apparatus for muffling, purification or even waste heatrecovery for an internal combustion engine, the engine exhaustbackpressure is greatly increased, the energy efficiency of an internalcombustion engine is reduced, and energy consumption is increased. Therise of the internal combustion engine energy consumption means morefossil fuel consumption, resulting in more pollution, which in turnresults in reducing the effects of the environmental protection andenergy-saving measures taken earlier.

So, while people are continuously developing the ‘pressure boost’technology, they are also seeking for technology of ‘depressurization’,such as the multi-valve technology which enlarges the exhaust gas flowspace by using multiple exhaust valves, so that the exhaust backpressureis reduced. For some special competitive occasions, such as racing, thepower of an internal combustion engine is required to give full play,even without installing a muffler aiming to reduce backpressure as muchas possible.

However, in a situation where the internal combustion engine is underlow load, if the exhaust backpressure is very low, due to the exhaustvalve being opened in advance, the fuel gas still having certainpressure will be discharged from the excessively clear exhaust valvebefore the piston reaches the bottom stop point, such that a portion ofpower is lost and the torque is reduced. It can be seen that keeping upa certain exhaust backpressure when the internal combustion engine isunder low load will instead increase the torque.

In summary, for the backpressure of an internal combustion engine, it isdesired that the backpressure is not too low when the internalcombustion engine is under low load, and however, it is desired that theexhaust backpressure is restrained to the greatest extent fromincreasing too rapidly. Only then the efficiency improvement of theinternal combustion engine can only be realized under all workingconditions thereof

SUMMARY OF THE INVENTION

In view of the existing desires for the exhaust backpressure of aninternal combustion engine, the present invention provides a new method,a new apparatus and a new system for optimizing exhaust backpressure ofan internal combustion engine. The present invention is based upon theprinciple: If the exhaust gas of an internal combustion engine israpidly cooled, the exhaust backpressure can be greatly reduced. So,when the internal combustion engine is under low load, a certain amountof exhaust resistance is arranged such that the backpressure will not goso far as to be too low; when the internal combustion engine is underhigh load, the exhaust gas is rapidly cooled so that the backpressurewill not go so far as to rise too rapidly.

A first object of the present invention is to provide a method foroptimizing exhaust backpressure of an internal combustion engine,comprising:

-   -   1) providing a damping member in an exhaust passage of an        internal combustion engine, and making an exhaust gas discharged        from an internal combustion engine passing through said damping        member;    -   2) cooling the exhaust gas before passing through said damping        member, or cooling the exhaust gas while passing through said        damping member.

By utilizing the method provided by the present invention the followingcan be achieved: a relatively higher exhaust backpressure when theinternal combustion engine is under low load, and the exhaustbackpressure will not rise too fast when the internal combustion engineis under high load. Specifically, allowing the exhaust gas discharged bythe internal combustion engine to pass through a damping member that iscapable of providing a certain amount of exhaust resistance produces adesired relatively high exhaust backpressure, so as to increase thetorque of the internal combustion engine when it is under low load. Theexhaust gas being rapidly cooled before or when it passes through thedamping member can achieve the purpose of increasing gas density of theexhaust gas and decreasing the flow rate of the exhaust gas. Thebackpressure is restrained from rising to fast when the internalcombustion engine is under intermediate, high load, so as to improve theefficiency of the internal combustion engine.

The present invention also provides an apparatus for optimizing exhaustbackpressure of an internal combustion engine, comprising:

-   -   1) a housing;    -   2) an exhaust gas inlet provided on the housing allowing an        exhaust gas to enter into an interior of the housing, an exhaust        gas outlet provided thereon allowing an exhaust gas to be        discharged out of the housing;    -   3) a damping member provided in the interior of the housing or        on the housing;    -   4) a cooling member provided in the interior of the housing for        cooling an exhaust gas.

Based on the above principle, mounting the apparatus provided by thepresent invention in the exhaust passage can not only provide a certainamount of exhaust resistance when the internal combustion engine isunder low load, but also makes the exhaust backpressure not rise toofast when the internal combustion engine is under high load. Especiallywhen the existing members having resistance, such as mufflers, in theexhaust passage is replaced with the apparatus of the present invention,the overall performance of the exhaust system can be preferablyimproved.

The present invention also provides another apparatus for optimizingexhaust backpressure of an internal combustion engine, comprising:

-   -   1) a housing;    -   2) an exhaust gas inlet provided on the housing allowing an        exhaust gas to enter into an interior of the housing, an exhaust        gas outlet provided thereon allowing a exhaust gas to be        discharged out of the housing;    -   3) a damping member provided in the interior of the housing or        on the housing;    -   4) a cooling water inlet provided on the housing allowing        cooling water to enter into the housing, a cooling water outlet        provided thereon allowing cooling water to be discharged out of        the housing;    -   said cooling water inlet, cooling water outlet, exhaust gas        inlet and exhaust gas outlet configured so that cooling water        and exhaust gas able to come in to contact with each other in an        interior of the housing.

Similarly, installing the apparatus in the exhaust passage can alsoachieve the purpose of optimizing exhaust backpressure of an internalcombustion engine.

The present invention also provides a system for optimizing exhaustbackpressure of an internal combustion engine, comprising an exhaustpassage of an internal combustion engine, wherein said system furthercomprises an apparatus for optimizing exhaust backpressure of aninternal combustion engine provided by the present invention, which ismounted in said exhaust passage of an internal combustion engine. Basedon the same principle, the present invention provides a system that canachieve the purpose of optimizing exhaust backpressure of an internalcombustion engine.

Utilizing the method, apparatus and system provided by the presentinvention can simply and efficiently enhance the power of an internalcombustion engine, reduce fuel consumption and enhance the specificpower of an internal combustion engine, and can be applied to variousdevices using internal combustion engine as the power.

The first principle of the present invention is: set a certain amount ofexhaust resistance, so that an internal combustion engine has a desired,relatively high exhaust backpressure when under low load.

The scheme to achieve its purpose is: to provide a damping member in theexhaust passage of an internal combustion engine, and allow the exhaustgas discharged from the internal combustion engine to pass through saiddamping member.

Here, the damping member is a member that can provide a certain amountof exhaust resistance, that is, the pressure drop produced before andafter exhaust gas passing through the damping member is a desiredpressure drop. Forms of the damping member may include: 1) reducing thecross-section of the exhaust passage of the internal combustion engine,or 2) dividing the exhaust gas into small tributaries, or 3) changingthe flow direction of the exhaust gas, or 4) other forms that canprovide a certain amount of exhaust resistance, or 5) a combination ofthe above forms.

The damping member is a member that can reduce the cross-section of theexhaust passage, such as an exhaust pipe with abruptly reducedcross-sections, or a member provided in the exhaust pipe and havingpores. It can be provided to abruptly reduce the cross-section of theexhaust passage of an internal combustion engine, so as to provide acertain amount of exhaust resistance. Such as, providing a baffle withpore in the exhaust pipe of an internal combustion engine, such that theexhaust gas can only pass through the pores. It also can be providedsuch that the exhaust pipe of an internal combustion engine abruptlybecomes thinner. In addition, the larger the extent to which thecross-section reduces, the larger the exhaust resistance.

The damping member may also be a member that can divide the exhaust gasinto a plurality of tributaries. Here, the way of the noted ‘divide theexhaust gas into a plurality of tributaries’ may be making the exhaustgas pass through a structure with a plurality of distributed pores, andthe exhaust gas is thus dispersed by the pores. The way used may also bemaking the exhaust gas pass through a structure with a plurality ofgaps, and the exhaust gas is thus dispersed by the gaps. By the methodof dividing the exhaust gas into small tributaries, a certain amount ofexhaust resistance can also be provided. In the method, the degree ofthe exhaust gas being divided can be adjusted depending on the desiredexhaust backpressure: the more the number of small tributaries intowhich the exhaust gas is divided, the thinner the divided smalltributaries, and the greater the exhaust resistance; vice versa.

The damping member may also be an exhaust pipe that can change the flowdirection of the exhaust gas. A certain amount of exhaust resistance canalso be provided if the flow direction of the exhaust gas is changed,such as by having a plurality of curved exhaust pipes.

The damping member referred to in the present invention can also beprovided in the interior of a housing, and cools the exhaust gasdischarged by the internal combustion engine in the interior of thehousing. So, the method provided by the present invention can alsoinclude: making the exhaust gas discharged by the internal combustionengine enter into the interior of the housing through an exhaust gasinlet on the housing, then discharge the cooled exhaust gas out of thehousing through an exhaust gas outlet on the housing. The damping membermay be located in the interior of the housing, such as by providing apore plate or padding with a large number of gaps in the interior of thehousing. In addition, the damping member may also be located on thehousing, such as an abrupt reducing of cross-sections existing from theinterior of the housing to the exhaust gas outlet on the housing.

Another principle of the present invention is: the high-temperatureexhaust gas of an internal combustion engine being rapidly cooled maygreatly reduce the flow rate of the exhaust gas, so that the exhaustbackpressure will not rise too fast when the internal combustion engineis under high load.

It is known in the prior art that: the existing structure of the exhaustpassage of the internal combustion engine having a certain amount ofexhaust resistance (e.g., an exhaust pipe, muffler, etc.), as the loadof the internal combustion engine increases, the gas displacement andthe exhaust temperature will rise with it, so that the flow rate rises,and due to the positive pressure, i.e. the resistance being proportionalto the square of the flow rate, the exhaust backpressure is thus causedto rise rapidly.

The applicant has found that before or when the exhaust gas isencountered with a certain amount of resistance, the exhaustbackpressure may be reduced if the exhaust gas temperature can berapidly lowered, thereby improving the efficiency of the internalcombustion engine.

The scheme of rapidly reducing the temperature of the exhaust gas maybe: 1) making the exhaust gas and the cooling liquid come into contactwith each other; or 2) dividing the exhaust gas into a plurality ofsmall tributaries, and then making the dispersed small tributaries heatexchange with the cooling medium, or 3) a combination of the above two.

If the high-temperature exhaust gas is made to come into direct contactwith a cooling liquid such as cooling water, the purpose of rapidcooling can be achieved. A preferable way is to keep the cooling waterflowing, such as the use of spray, discharging the cooling water whichhas absorbed heat, and the exhaust gas continuously contacting the newcooling water, thus the cooling effect will be better.

Here, the cooling water source can be determined based on the specificcircumstances.

The cooling water used as the cooling fluid may come from an externalindependent water system of the immediate natural environment, forexample, taken from the natural water body such as seawater or inlandfreshwater naturally existing. As to the apparatus (such as vessels)that use the internal combustion engine as the power on the ocean orfreshwater, the cooling water may be directly extracted from theseawater or freshwater of the immediate nature environment, or, theseawater or freshwater may be firstly stored in a water storingapparatus such as water tank, water tower, the cooling water is obtainedfrom the water storing apparatus. The cooling water which has absorbedheat may be directly discharged to the immediate natural environment;also the cooling water which has absorbed heat may be processed beforebeing discharged to the immediate natural environment. Thus, the methodprovided by the present invention also includes: extracting coolingwater from a natural water body and convey it to the housing. The systemprovided by the present invention also includes an apparatus, such as acooling water intake pipe installed with a pump, which is able toextract cooling water from a natural water body and convey it to thehousing, the cooling water intake pipe communicating with the coolingwater inlet of the housing.

The cooling water of the internal combustion engine may also be reusedto be used as the cooling water for cooling the liquid. Most apparatusthat uses internal combustion engine as the power, such as vehicles,vessels, etc., per se, have a set of cooling water system of internalcombustion engine. In this case, the cooling water may be taken from thecooling water system of the power apparatus itself. Therefore, themethod provided by the present invention also includes conveying thecooling water of an internal combustion engine to a housing. The systemprovided by the present invention also includes an apparatus that isable to convey the cooling water of an internal combustion engine to ahousing.

The cooling water used as the cooling liquid may be used combining theabove two methods, both using the cooling water from a natural waterbody and using the cooling water of the internal combustion engine.

The cooling water used as the cooling liquid may also be recycled. Thecooling water discharged from the housing, which has absorbed heat ofthe high-temperature exhaust gas, may be directly discharge out ordischarged after being processed, and may also be recycled. For example,the cooling water absorbing heat after cooling the high-temperatureexhaust gas may flow through a heat exchanger, being cooled beforeentering the housing again as the cooling water.

The cooling water may be allowed to come into contact with the exhaustgas of an internal combustion engine in an interior of a housing,thereby achieving the purpose of rapidly reducing the temperature of theexhaust gas. Therefore, the method provided by the present invention mayalso include: making the cooling liquid enter into the interior of thehousing through the cooling water inlet of the housing, and dischargingthe cooling liquid which has absorbed heat from the exhaust gas out ofthe housing through the cooling water outlet of the housing.

The exhaust gas of the internal combustion engine may be allowed toenter from the exhaust gas inlet on a housing, and be discharged fromthe exhaust gas outlet, forming an exhaust gas flow path. In addition,the cooling water may be allowed to enter from the cooling water inletof the housing, and be discharged from the cooling water outlet, forminga cooling water flow path. The exhaust gas inlet abovementioned refersto any opening that allows fluid enter into the interior of the housing,which may be a direct opening on the wall of the housing, then, througha connecting member, communicates with the pipe for conveying liquid.The housing may also be integrally molded with the conveying pipe. Theconveying pipe may also extend into the interior of the housing, sothat, the exhaust gas inlet refers to the pipe orifice extending intothe interior of the housing. The cooling water inlet, cooling wateroutlet and the exhaust gas outlet may also use the various forms asabovementioned.

The housing used by the present invention is a closed housing, that is,except the positions of abovementioned exhaust gas inlet, exhaust gasoutlet, cooling water inlet, cooling water outlet, the other parts areall sealed, and the gas or liquid entering the housing can only enterand exit from the abovementioned inlets and outlets.

In order to achieve the purpose of rapid cooling of the exhaust gas, inthe method and apparatus provided by the present invention, the exhaustgas of an internal combustion engine and the cooling water are requiredto come into contact with each other, that is, the flow path of theexhaust gas of the internal combustion engine and the flow path of thecooling water are made to overlap with each other.

If a more optimal cooling effect is desired, one preferred embodiment isto make the exhaust gas of the internal combustion engine and thecooling water to contact reversely or/and laterally, that is, the flowdirection of the exhaust gas and the flow direction of the cooling waterare away from each other or facing each other, or nearly away from eachother or facing each other. If the cooling water inlet is made to belocated downstream of the exhaust gas flow, and the cooling water outletis located upstream of the exhaust gas flow, the cooling water andexhaust gas thereby may reversely contact, such that the contact is moreadequate. Therefore, in a preferred embodiment, the exhaust gas of theinternal combustion engine and the cooling water reversely contact. In amore preferred embodiment, the exhaust gas of the internal combustionengine pass through the interior of the housing from bottom to top, andthe cooling water pass through the interior of the housing from top tobottom, allowing them to reversely contact. The advantage thereof isthat the exhaust gas of the internal combustion engine may disperse inthe interior of the housing more adequately, and the cooling water mayflow by fully utilizing the gravity effect, other than applying extrapressure to maintain its flowing. Thus, the cooling water inlet may beconfigured to be higher than the cooling water outlet in the gravitydirection, so that the cooling water entering the housing through thecooling water inlet passes through the interior of the housing from topto bottom; the exhaust gas inlet is lower than the exhaust gas outlet inthe gravity direction, so that the exhaust gas entering the housingthrough the exhaust gas inlet passes through the interior of the housingfrom bottom to top. Thus, the cooling water and the exhaust gas mayreversely contact, thereby the contact is more adequate.

In order to further enhance the full contact of the cooling water andthe exhaust gas, one can think of ways to improve the degree ofdispersion of the cooling water entering the housing. For instance, oneor more water distributor composed of spraying member with a pluralityof pores, arranged uniformly on the upper side of the interior of thehousing, spraying the cooling water onto the entire interior of thehousing to the best of it, so that the cross-section of the housing canbe uniformly distributed with water. Thus, the method provided by thepresent invention also includes: dispersing the cooling water enteringthe interior of the housing. The housing of the apparatus provided bythe present invention is also provided with a member dispersing thecooling water entering into the interior of the housing, such as a waterdistributor.

In a more preferred embodiment, in order to not allow the cooling waterfrom entering the exhaust pipe of the internal combustion engine fromthe exhaust gas inlet, the cooling water outlet may be configured to belower than the exhaust gas inlet in the gravity direction. Thus, beforethe liquid surface of the cooling water flowing to or falling onto thebottom of the housing reaches the position of the exhaust gas inlet, thecooling water is already discharged from the cooling water outlet.

In addition, the bottom of the casing may also be provided with a waterseal, making the liquid surface of the cooling water higher than thecooling water outlet and lower than the exhaust gas inlet. Thus, theexhaust gas will not flow out from the cooling water outlet. Further,providing a water seal makes the cooling water not enter the exhaust gasinlet, even if the angle of inclination of the water seal liquid surfacein all direction reaches 22.5 °.

In a more preferred embodiment, the exhaust gas inlet is located on thelower portion of the side surface of the housing, and the exhaust gasoutlet is located at the top of the housing, and the exhaust gas outletmay connect directly to the chimney, discharging directly the exhaustgas into the atmosphere. The cooling water inlet is located on the upperportion of the side surface of the housing, and the cooling water outletis located on the lower portion of the side surface. Moreover, in thegravity direction, the cooling water outlet is lower than the exhaustgas inlet. In a most preferred embodiment, the exhaust gas inlet islocated at the bottom of the housing, and the exhaust gas outlet islocated at the top of the housing, so that the exhaust gas inlet mayconnect directly to the exhaust pipe of the internal combustion engine,and the exhaust gas outlet connects directly to the chimney, dischargingthe exhaust gas directly into the atmosphere.

If the exhaust gas is divided into small tributaries, and then thedispersed small tributaries heat exchange with a cooling medium, so thatthe efficiency of heat exchange between the exhaust gas and the coolingmedium can be greatly improved, thereby achieving the purpose of rapidlyreducing the exhaust temperature, so that the exhaust backpressure willnot rise too face when the internal combustion engine is under highload. Another effect of cooling the exhaust gas in this way is: suchthat the exhaust backpressure will not be too low when the internalcombustion engine is under low load, thereby achieving the effect ofoptimizing the exhaust backpressure under all working conditions.

Here, the way of the abovementioned ‘dividing the exhaust gas into smalltributaries’ may be making the exhaust gas pass through a structure withpores distributed therein, and the exhaust gas is thus dispersed by thepores. The way used may also be making the exhaust gas pass through astructure having gaps, such as a heat dissipating sheet, and the exhaustgas is thus dissipated by gaps.

Here, the cooling medium may be gases having endothermic properties,such as air, hydrogen, etc. Then the cooling medium may be made to comeinto contact with the exhaust gas, which is divided into smalltributaries, through the cooling member, so that the exhaust gas iscooled. The cooling member may be a heat dissipating sheet or radiatormade of materials having good heat transfer properties, such as a metalmaterial. A part of the cooling member is located in the housing, and apart outside the housing, being able to rapidly transfer the heat of theexhaust gas in the housing to the outside of the housing to be released.In this case, the process of heat exchange between the exhaust gas andthe cooling member is at the same time the process of the exhaust gasbeing divided into small tributaries. Here, the cooling medium may alsobe in the form of a combination of cooling member and fluid, such as theflowing cooling water being encapsulated in a metal pipe, which can alsoachieve the purpose of rapid cooling. The benefit of doing so is thatthe cooling water in the pipe may generate vapor, the heat of which maybe conveniently and directly utilized. For example, heat exchange isperformed between a heat exchanger of tubular, plate, tube-wall orfinned tube, and the exhaust gas. Similarly, when the high-temperatureexhaust gas passes through the heat exchanger, it is divided into smalltributaries to then perform heat exchange with the heat exchanger aswell.

As described above, when the internal combustion engine is under highload, the backpressure is desired to be as low as possible. While in theprior art, the exhaust resistance of the structure (such as a muffler)provided in the exhaust passage of the internal combustion engine isrelatively small. Therefore, in the case of the internal combustionengine being under low load, the desired exhaust backpressure cannot beachieved. In this way, the process of dividing the exhaust gas intosmall tributaries is also the process of providing a certain amount ofexhaust resistance. The degree of the exhaust gas being divided can beadjusted depending on the desired exhaust backpressure. The more thesmall tributaries of the exhaust gas divided, the thinner the smalltributaries divided, the greater the exhaust resistance; vice versa.

Accordingly, in this way, the purpose of optimizing exhaust backpressureof an internal combustion engine under all working conditions can berealized.

For the cooling of the exhaust gas, the most preferred way is to dividethe exhaust gas into small tributaries, which is then cooled by way ofmaking which and the cooling liquid (such as cooling water) come intocontact with each other. For example, the exhaust gas is made to passthrough a member having a large amount of gaps, to be divided into aplurality of small tributaries which in said gaps come into contact withthe cooling liquid. In a preferred embodiment of the present invention,the housing is filled with padding which form gaps thereinbetween,thereby forming a padding layer having a large number of gaps which is amember which can divide the exhaust gas into a plurality of smalltributaries, i.e. the damping member. Padding containing gaps therebyhaving a large specific surface area may be included in the housing, forthe purpose that a large number of pores are formed in at least a partof the space inside the housing. Thus, the cooling fluid has to bedispersed when passing through the pores between the padding, in whichthe cooling fluid and the exhaust gas may fully contact. When thecooling liquid is cooling water, the form of padding may be selected tobe the common bulk padding as Pall rings, Raschig rings or other saddlerings, also may be selected to be a common structured padding. Thepadding texture is preferred to be weatherproof materials like metal,ceramics, etc., and also can be selected to be polymer materials, suchas polypropylene, polyethylene, or ABS engineering plastics, etc., orthere kinds of materials may be used in combination. Thehigh-temperature exhaust gas is divided into small tributaries whenpassing through this padding having a large specific surface area,preferably making the cooling liquid like cooling water come into directcontact with the high-temperature exhaust gas in said padding, allowingthe high-temperature exhaust gas to be cooling rapidly. Therefore, inthe method and apparatus provided by the present invention, the housingis filled with padding which can form gaps thereinbetween, forming apadding layer with a large number of gaps. The method provided by thepresent invention also includes: the exhaust gas is made to pass througha padding layer having a large number of gaps.

In addition, if the cooling fluid is selected to be cooling gas, such asair, the purpose of rapid cooling may also be achieved. In this case,the padding is preferably selected to be ceramic, enamel and metalmaterials, and these kinds of materials may be used in combination.

The method or apparatus provided by the present invention is speciallysuited for a turbocharged internal combustion engine, where the exhaustgas discharged by the internal combustion engine passes through aturbocharger impeller and works, before entering the housing from thegas inlet of the housing. Accordingly, the method provided by thepresent invention also includes: the exhaust gas discharged by theinternal combustion engine passes through the turbocharger impeller andworks before entering the housing. The exhaust passage of the internalcombustion engine of the system provided by the present invention may bean exhaust passage of high-temperature exhaust gas, which is connectedto the exhaust outlet at the exhaust gas side of the turbocharger.

Further, as the exhaust passage of current internal combustion engine isnormally provided with one or more of a muffler, exhaust gaspurification and waste heat recycling apparatus or devices. If theseapparatus are arranged in the exhaust passage of the internal combustionengine, a certain amount of exhaust resistance will be provided,providing pressure drop in the exhaust path of the exhaust gas, andthese apparatus are the apparatus that can make exhaust gas dischargeproduce a pressure drop. The more the pressure drop is, the greater theexhaust resistance is, leading to a higher exhaust backpressure.

According to the apparatus or devices through which the exhaust gas ofthe internal combustion engine passes before eventually discharged intothe atmosphere, and to the different order of passing through theseapparatus or devices, the method of the present invention has at leastthe following several applications: that is, the present method isapplied before or after the exhaust gas passing through the aboveapparatus or devices, or the apparatus for optimizing backpressureaccording to the present invention is made to achieve the functions ofthe above apparatus or devices at the same time of optimizingbackpressure, so as to replace the above apparatus or devices.

Thus, the system provided by the present invention may possibly hasseveral ways described as follows, wherein, for convenience ofdescription, in the following content, P₀ is set to be the externalatmospheric pressure. In addition, the pressure drop caused by theresistance of the exhaust pipe is ignored, and pressure drop ΔP is usedto represent the local pressure drops of one or more other exhaust gastreatment apparatus and devices. As the gas flow passes through thedamping member is the apparatus of the present invention, the coolingapparatus per se will bring in a pressure drop ΔP_(i). Here it should benoted that, when the load of the internal combustion engine rises, theflow rate were to be increased rapidly, but due to the high-temperatureexhaust gas being cooled rapidly with increased density and decreasedvolume, the flow rate thereby is lowered rapidly. Thus, in the case of arelative high-temperature exhaust, the rising range of ΔP_(i) is smallwhen the load of the internal combustion engine is increasing. In thiscase, as the flow rate is an exponential relationship with the positivepressure, the positive pressure or resistance caused by the decrease ofthe flow rate is still decreasing, even taking into consideration of thefactor of the increase brought to the positive pressure by the increaseof the exhaust gas density.

When there is no other exhaust gas treatment apparatus and device in theexhaust pipe, the exhaust backpressure of the internal combustion enginethen is approximately to be the sum of the external atmospheric pressureP₀ and the pressure drop ΔP_(i) of the cooling apparatus per se, i.e.:

P=P ₀ +ΔP _(i)

Thus, when the internal combustion engine is under low load, due to thepresence of ΔP_(i), the torque of the internal combustion engine may beimproved. When the load of the internal combustion engine is increasing,as described above, the rising range of ΔP_(i) is small, so theinfluence on the backpressure P is limited.

If the exhaust passage is also installed with other apparatus thereinwhich increases the exhaust backpressure, such as a muffler, and islocated downstream of the apparatus provided by the present invention,then, the exhaust gas discharged by the internal combustion enginefirstly passes through the apparatus provided by the present invention,and then through other apparatus or device for exhaust gas treatment,and after that, passes through the pipe and is discharged into theatmosphere. The exhaust backpressure P is approximately equal to the sumof external atmospheric pressure P₀ and pressure drop ΔP_(i) of theapparatus per se of the present invention and other apparatus or devicefor exhaust gas treatment, i.e.:

P=P ₀ +ΔP+ΔP _(i)

Although, in comparison with the case in which the apparatus of thepresent invention is not used, the newly introduced apparatus of thepresent invention produces a pressure drop ΔP_(i), but as thehigh-temperature exhaust gas when the internal combustion engine isunder intermediate and high load is rapidly cooled when passing throughthe apparatus of the present invention, so that the flow rate is largelydecreased. As the pressure drop is proportional to the square of theflow rate, so the pressure drop ΔP when the cooled exhaust gas flowpasses through the above described other apparatus or device for exhaustgas treatment is largely decreased in comparison with that when thehigh-temperature exhaust gas passes through, thereby improving theefficiency of the internal combustion engine. Moreover, in this case, asdescribed above, when the internal combustion engine is under low load,the effect of improving the torque of the internal combustion engineexists, similarly.

According to the above description, if there is other apparatus forexhaust gas treatment installed in the exhaust passage, the exhaustbackpressure will be adversely affected. However, in some cases, forenvironmental or other objects, it is necessary to install an apparatusfor exhaust gas treatment, such as a muffler, in the exhaust passage.Therefore, if multiple functions can be integrated by the apparatusprovided by the present invention, for instance, the apparatus is madeto simultaneously have the muffling function, thereby the exhaustbackpressure can be further optimized.

When other apparatus or device for exhaust gas treatment can be omittedif their functions are integrated with the apparatus of the presentinvention, this case is similar to the case in which the apparatus ofthe present invention is separately installed. Then, the exhaustbackpressure of the internal combustion engine is approximately equal tothe sum of external atmospheric pressure P₀ and the pressure drop ΔP_(i)of the apparatus per se of the present invention, i.e.:

P=P ₀ +ΔP _(i)

This means that the pressure drop ΔP brought by other apparatus ordevice for exhaust gas treatment can be eliminated, and the exhaustbackpressure is greatly decreased relative to the original situation,thereby improving the efficiency of the internal combustion engine.Similarly, due to the existence of ΔP_(i), the torque when the internalcombustion engine is under low load is increased. Thus it can be seenthat a more preferred scheme is that the apparatus of the presentinvention can integrate the functions of other apparatus or device forexhaust gas treatment, and then to replace these apparatus or devicesfor exhaust gas treatment. This replacement is precious for spatialresource, for instance, very important for a floating platform likevessel, etc., equipped with a muffler and a waste heat boiler.

It should be noted that, from the above description, it can be seen thatthe principle of the cooling apparatus integrating the waste heatrecycling of the waste heat boiler lies in the recycling of the heatabsorbed after the heat exchange between the cooling fluid and thehigh-temperature exhaust gas. The principle of integrating the mufflingfunction of the muffler lies in that the effects of the exhaust gas,passing through the apparatus of the present invention, being divided bycross-section expansion and gas flow alteration, the two of which aretheoretically and realistically not contradictory. Therefore, thecooling apparatus of the present invention may simultaneously integratethe functions of waste heat recycling and muffling.

In order to prevent noise pollution, at present, the exhaust passage ofthe internal combustion engine is generally mounted with the muffler,which is also a main member causing the rise of the exhaust backpressureof the internal combustion engine. The applicant has found that, if theexhaust gas entering the housing can be rapidly cooled, the function ofenhancing the muffling effect can be realized.

Based on the muffling principle, there are different types of mufflerslike resistive muffler, reactive muffler and impedance compositemuffler. A resistive muffler mainly uses porous sound-absorbingmaterials to reduce noises. When sound waves enter the resistivemuffler, part of the sound energy is turned into heat by friction in thepores of the porous material to be dissipated, making the sound wavepassing through the muffler be weakened. A resistive muffler has goodeffect on intermediate and high frequency, and poor effect on lowfrequency. A reactive muffler is combined from chambers and ducts withabrupt interfaces, making use of abrupt expansion or contraction of thecross-section of the pipe to reflect back the sound waves of certainfrequencies transmitting along the pipe at the position of sudden changeto the direction of the sound source, so as to achieve the purpose ofmuffling. The reactive muffler is suitable for eliminating noise oflow-to-intermediate frequency, and is poor for high-frequency noise.Combining the resistive structure and reactive structure in a certainmanner, an impedance composite muffler is formed, which has mufflingcharacteristics of both.

In order to achieve good muffling effect, the following schemes havebeen found which facilitate enhancing the muffling effect: 1) multiplechanges in the direction of air flow, 2) the air flow repeatedly passingthrough cross-sections first contracting and then expanding, 3) dividingthe air flow into a plurality of small tributaries and flow along aplurality of unsmooth planes, 4) cooling the air flow.

For an internal combustion engine, on one hand, a muffler is essential,based on the requirements of environmental protection, and on the otherhand, the muffling effect is constrained by the result of the rise ofthe backpressure. Therefore, the existing muffling technology for aninternal combustion engine is often not good to meet these expectations.For a resistive muffler, a plurality of pores are needed to be providedin the muffler to change and divide the air flow. The more, longer, moreirregular the pores, the better the resistive muffling effect, but theexhaust backpressure caused by the muffler is also greater and the lossof power that the internal combustion engine can withstand is limited.For reactive muffling, the greater the expansion magnification of thecross-section of the exhaust passage, that is, the greater the volume ofthe muffler, the more favorable for muffling. However, for mostoccasions, especially for ships etc. which have limited accommodatingspaces, the way of cross-section expansion is difficult to apply. As to‘cooling’ of the air flow, the existing muffling technology is even moredifficult to achieve, particularly in the muffler in a dense space of aship, where not only the cooling cannot be achieved, but to prevent ahigh-temperature of several hundred ° C. burning the surroundingfacilities and personnel, insulation materials have to be used for atight wrapping up for ‘preserving heat’.

The method or apparatus provided by the present invention can make useof the principle of reactive muffling to effect muffling. Therefore, inthe method or apparatus provided by the present invention, abruptexpansion of cross-section is formed from the exhaust gas inlet to theinterior of the housing. Here, the method or apparatus provided by thepresent invention at least makes use of the principle of reactivemuffling. A reactive muffler is combined from chambers and ducts withabrupt interfaces, making use of abrupt expansion or contraction ofcross-section of the pipe to reflect back the sound waves of certainfrequencies transmitting along the pipe at the position of sudden changeto the direction of the sound source, so as to achieve the purpose ofmuffling. In the method and apparatus provided by the present invention,abrupt expansion of cross-section is formed from the exhaust gas inletto the interior of the housing. The abrupt expansion of cross-sectionhere refers to reducing noise of the exhaust gas by making use of thereactive muffling principle.

If the casing is made into a regular shape, e.g. a cylindrical or otherregular shape, tested by the applicant, when the cross-sectional area ofthe exhaust gas inlet is 0.05 to 0.5 times the housing of thecross-sectional area, the muffling effect is very significant.Accordingly, in a preferred embodiment, the exhaust gas inletcross-sectional area is 0.05 to 0.5 times the cross-sectional area ofthe housing. The Applicant has also proved that when the housing volumeis 3 to 30 times the displacement of the internal combustion engine, themuffling effect of apparatus is more remarkable, therefore, in a morepreferred embodiment, the volume of the housing 3 is ˜30 times thedisplacement of the internal combustion engine.

The muffling method provided by the present invention may further takeadvantage of the principle of resistive muffling to enhance the mufflingeffect. The exhaust gas can be divided into small tributaries. Accordingto the principle of muffling, the exhaust gas is divided into a smalltributary to enhance the muffling effect.

If the housing is filled with padding capable of forming gapsthereinbetween, the muffling effect may be further enhanced. Thepresence of padding makes the apparatus a resistive muffler. When theexhaust gas enters into the padding, part of the sound is turned intoheat by friction in the pores of the porous material to be dissipated,so that the sound waves through the muffler are weakened. The Applicanthas also found that a large area of contact of the liquid with theexhaust gas flow, per se, can absorb the energy of sound waves tofacilitate muffling.

Thus, the present invention belongs to the impedance composite muffling,which has muffling characteristics of both resistance and reactance.Further, the present invention cools the high-temperature exhaust gas ofhundreds of degrees Celsius down to tens of degrees Celsius, flowingthrough the muffler, producing the expansion cooling effect whileenhancing the effect of the resistance and reactance. A resistivemuffler of the present invention mainly makes use of a large number ofpores formed in materials such as the padding, since the exhaust gas iscooled, the volume is contracted, and the flow rate is decreased, theresistance generated when flowing through a large number of pores isdecreased by a greater range. Therefore, it is possible to use morepadding to make up more, longer and more irregular pores, which makesthe following of the present invention all higher than existing mufflertechnology by several orders: frequency of changes in the direction ofairflow, the number of the times of repetition of airflow passingthrough cross-sections first contracting and then expanding, the numberof the small tributaries divided from the gas stream, and the area of anunsmooth passage formed. On the other hand, the reactive muffling of thepresent invention is achieved from abrupt expansion of thecross-sections formed from the exhaust gas inlet to the interior of thehousing. Due to the technical solution of the present inventionsignificantly reduces the exhaust gas volume, which is equivalent toincreasing the expansion magnification of the cross-section of theexhaust passage, further enhancing the reactive muffling effect. Fromanother perspective, in the occasions where a great expansion ratio isrequired and the prior art is difficult to achieve by space limitations,the method or apparatus provided by the present invention can achievethat very well.

The method of muffling exhaust gas of an internal combustion engine,provided by the present invention, at the same time, has theabove-mentioned effect of optimizing the exhaust backpressure of aninternal combustion engine. Thus, by using the method provided by thepresent invention, the effect of optimizing the exhaust backpressure ofan internal combustion engine can be achieved as well as muffling effectis achieved by using the same apparatus. In this way, the apparatus ofthe present invention is mounted to the exhaust passage of an internalcombustion engine, so there is no need to install an additional muffleron the ship. Due to the relevant provisions of the existing regulationson the muffling and energy saving, in the existing structure of theship, the exhaust passage of an internal combustion engine is installedwith a waste heat boiler and a muffler. Moreover, in the position of theexhaust path of the internal combustion engine, there is no extra spacefor installing the apparatus for optimizing the exhaust backpressure ofinternal combustion engine. By use of the method provided by the presentinvention, this problem can be well solved, that is, to install theapparatus provided by the present invention in the position of theexisting muffler and replace the existing muffler.

Further, since cooling the exhaust gas itself can achieve the effect ofmuffling, the present invention also provides a muffling method forexhaust gas of an internal combustion engine, including: making theexhaust gas discharged from the internal combustion engine enter intothe interior of the housing through an exhaust gas inlet of the housing,and in addition, said method further including: making the exhaust gasentering into the interior of the housing to come into direct contactwith the cooling liquid.

The present invention also provides a apparatus for muffling the exhaustgas of an internal combustion engine, including: a housing, the housingis provided with an exhaust gas inlet allowing the exhaust gas to enterinto the interior of the housing, an exhaust gas outlet allowing theexhaust gas to be discharge out of the housing, a cooling water inletallowing the cooling liquid to enter into the interior of the housing, acooling water outlet allowing the cooling liquid to be discharged out ofthe housing; said cooling water inlet, cooling water outlet, exhaust gasinlet and exhaust outlet are configured so that the cooling liquid andthe exhaust gas may come into contact with each other within thehousing.

The present invention also provides a system for muffling exhaust gas ofan internal combustion engine, said system comprising an exhaust passageof the internal combustion engine, said system further comprising anapparatus for muffling exhaust gas of an internal combustion engineprovided by the present invention, the apparatus is installed in theexhaust passage of the internal combustion engine.

By using the method, apparatus and system for muffling exhaust gas of aninternal combustion engine provided by the present invention, theexisting muffler can be replaced, without the need to install othermuffler. For an apparatus which can conveniently utilize cooling water,such as vessel sailing on natural water, can be muffled by the method,apparatus or system, provided by the present invention, for mufflingexhaust gas of an internal combustion engine. For an apparatus using aninternal combustion engine as a power on the land, such as cars, canalso use the cooling water of an internal combustion engine as thecooling liquid, so as to proceed muffling of the exhaust gas of aninternal combustion engine, by the method, apparatus and system providedby the present invention.

The method, apparatus and system for muffling exhaust gas of an internalcombustion engine can also be functionally combined with existingmuffler. For example, an abrupt expansion of cross-section is formedfrom the exhaust gas inlet to the interior of the housing, thus, rapidcooling of the high-temperature exhaust gas will further enhance theresistance muffling effect.

In the method, apparatus and system for muffling exhaust gas of aninternal combustion engine, provided by present invention, the way ofcooling water, contact between cooling water and high-temperatureexhaust gas as well as the configuration of inlet and outlet can be thesame as or similar to the method, apparatus and system for optimizingexhaust backpressure of an internal combustion engine as describedabove.

Data shows that the diesel engine exhaust gas and cooling medium takeaway heat about 50% of the total fuel heat, most of which is dischargedin the form of high-temperature exhaust gas into the atmosphere. Theexisting shipbuilding regulations, in addition to environmentalregulations on muffling, also requires installing waste heat boiler inthe exhaust passage of an internal combustion engine. The waste heatboiler, also known as exhaust gas boiler, the role of which is torecycle the heat in the exhaust gas, in order to achieve the purpose ofenergy saving. The structure of the existing waste heat boiler is a ductencapsulating cooling water, located in the exhaust passage of theinternal combustion engine. Thus a contradiction exists: If it isdesired to more fully recover waste heat, the pipe encapsulating thecooling water and the exhaust gas of an internal combustion engine isrequired to fully contact, which would require the pipe encapsulatingthe cooling water are more densely distributed in the exhaust pipe ofthe internal combustion engine, which is bound to increase exhaustresistance and the exhaust backpressure, and thereby adversely affectthe effectiveness of the internal combustion engine. It is also becauseof this, the waste heat boiler in the existing vessels does not havehigh heat recovery efficiency.

In various embodiments of the method and apparatus provided by thepresent invention, if the cooling liquid (cooling water) is in directcontact with the exhaust gas for cooling exhaust gas, the cooling water(i.e., hot water) having absorbed heat of the high-temperature exhaustgas can be discharged and utilize the heat therein. Thus, the method andapparatus provided by the present invention can also perform a wasteheat recovery function. Accordingly, the method provided by the presentinvention further comprises: conveying the cooling liquid which hasabsorbed heat of the high-temperature exhaust gas to the heatutilization apparatus or heat exchanger. The system provided by thepresent invention further comprises a heat utilization apparatus or heatexchanger, and a duct for conveying fluid to the heat utilizationapparatus or heat exchanger.

Some transportation of goods such as heavy oil, asphalt etc. needs heatsource to preserve heat; hot water can be utilized directly; theapparatus using hot water to preserve heat is a heat utilizationapparatus. Some transportation of other goods, such as refrigeratedtransport vessels also need a heat source (specific scheme belonging tothe scope of conventional design) is used for cooling, the recoveredwaste heat by the scheme of the present invention can meet all or partof heat requirements thereof.

Since the method and apparatus of the present invention make use of acooling liquid such as cooling water to absorb the large amount of heatthat brought by the high-temperature exhaust gas that is originally tobe discharged into the atmosphere at the same time of improving theefficiency of the internal combustion engine. The cooling water whichhas absorbed heat from the exhaust gas becomes the intermediate hot, andcan be directly used again, and can also be reused after beentransferred into clean hot water by way of a liquid-liquid heat exchangewith high heat exchange efficiency. For example, a ton class ship hasexhaust emissions of about 1220 kg/h, the temperature of the exhaust gasdischarged to the atmosphere exceeds 300° C. under MCR conditions (80%of the rated power), the heat of which is all abandoned. The temperatureof the exhaust gas discharged to the atmosphere through the apparatus ofthe present invention is stabilized at about 50° C. or 30° C. when theship is under MCR working conditions, allowing the heat of millions ofcalories per hour that is formerly abandoned to be recycled.Accordingly, the waste heat boiler on the exhaust pipe of the originalinternal combustion engine may be completely substituted by the presentapparatus. Meanwhile, the recycled waste heat is used to produce hotwater and/or steam as required.

For this purpose, the cooling water pump of the apparatus of the presentinvention is also designed to adjust the size of the flow, by changingthe amount of cooling water to achieve temperature adjusting of the hotwater produced, so as to better adapt to the need for utilization ofwaste heat, to further improve the efficiency of waste heat utilization.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of the apparatus for optimizing exhaustbackpressure of an internal combustion engine, according to a firstembodiment of the present invention;

FIG. 2 is a schematic diagram of the system for optimizing exhaustbackpressure of an internal combustion engine, according to a firstembodiment of the present invention;

FIG. 3 is a schematic diagram of the correlation between exhaustbackpressure and engine load rate, according to a first embodiment ofthe present invention;

FIG. 4 is a schematic diagram of the correlation between exhausttemperature and engine load rate, according to a first embodiment of thepresent invention;

FIG. 5 is a schematic diagram of the apparatus for optimizing exhaustbackpressure of an internal combustion engine, according to a secondembodiment of the present invention;

FIG. 6 is a schematic diagram of the system for optimizing exhaustbackpressure of an internal combustion engine, according to a thirdembodiment of the present invention;

FIG. 7 is a schematic diagram of the system for optimizing exhaustbackpressure of an internal combustion engine, according to a forthembodiment of the present invention;

FIG. 8 is a schematic diagram of the apparatus for optimizing exhaustbackpressure of an internal combustion engine, according to a fifthembodiment of the present invention;

FIG. 9 is a schematic diagram of the apparatus for optimizing exhaustbackpressure of an internal combustion engine, according to a sixthembodiment of the present invention; and

FIG. 10 is a schematic diagram of the apparatus for optimizing exhaustbackpressure of an internal combustion engine, according to a seventhembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 to FIG. 4 show the apparatus and system for optimizing exhaustbackpressure of an internal combustion engine according to the firstembodiment of the present application.

As shown in FIG. 1, in this embodiment, the apparatus for optimizingexhaust of an internal combustion engine comprises housing 6 providedwith a cooling water inlet 10 and a cooling water outlet 11. Wherein,cooling water inlet 10 is located on the upper portion of the sidesurface of the housing, and cooling water outlet 11 is located on thelower portion of the side surface of the housing. Under the effect ofgravity, cooling water entering the housing from cooling water inlet 10pass through from top to bottom, and is discharged through cooling wateroutlet 11.

The housing 6 is also provided with an exhaust gas intake pipe 8 and anexhaust gas outlet 9. Wherein, the exhaust gas intake pipe 8 extendsinto the interior of the housing, the pipe orifice extending into theinterior of the housing being an exhaust gas inlet 7. The exhaust gasinlet 7 is located at the bottom of the housing, and the exhaust gasoutlet 9 is located at the top of the housing. The exhaust gas enteringhousing 6 from exhaust gas inlet 7 passes through in the interior of thehousing from bottom to top and is discharged through exhaust gas outlet9.

Wherein, the cooling water outlet 11 is located below the exhaust gasinlet 7 in the direction of gravity, so that the cooling water flowingto or falling onto the bottom of the housing does not enter exhaust gasintake pipe 8 through exhaust gas inlet 7 under the effect of gravity.

Padding which forms gaps thereinbetween is filled within the housing 6,form padding layer 12. A water distributor 14 is provided above paddinglayer 12.

Further, in order to prevent the cooling water from entering exhaust gasintake pipe 8 from exhaust gas inlet 7, a water baffle 13 is alsoprovided between exhaust gas inlet 7 and padding layer 12. Water baffle13 is located right above exhaust gas inlet 7, completely blocking theliquid from top to bottom in the vertical direction to not allow theliquid into exhaust gas inlet 7. The edge part of the upper surface ofwater baffle 13 is lower than the central part, so that the rinsingwater flowing to or falling onto water baffle 13 further flows to orfalls onto the bottom of the housing, which further prevents the rinsingwater from entering exhaust gas inlet 7.

Hereby exhaust gas intake pipe 8 and exhaust gas inlet 7 are configuredto make exhaust gas smoothly reaches inlet 7, and avoiding water baffle13, and then enters into the housing, in order that the high-temperatureand high velocity exhaust gas discharged from an internal combustionengine does not turn direction suddenly before reaching exhaust gasinlet 7 due to the obstruction of water baffle 13, causing a largeexhaust resistance.

As shown in FIGS. 1 and 2, in use, apparatus 5 for optimizing exhaustbackpressure is mounted in the exhaust passage of an internal combustionengine of a ship, the apparatus together with the exhaust passage of aninternal combustion engine constituting a system for optimizing exhaustbackpressure of an internal combustion engine. The internal combustionengine of the ship is equipped with a turbocharger 2 thereon. In theexisting structure of a ship, an exhaust passage of an internalcombustion engine is installed with a waste heat boiler and a muffleraccording to the relevant provisions of the existing regulations onmuffling and energy efficiency; moreover, there is no surplus space forfurther installation of device with large dimensions in the place wherethe exhaust passage of the exhaust gas from an internal combustionengine. In the present embodiment, apparatus 5 for optimizing exhaustbackpressure of an internal combustion engine is mounted in a muffler'sposition in an existing ship, replacing the original muffler and wasterheat boiler. Exhaust gas intake pipe 8 communicates with exhaust pipe 3of an internal combustion engine, and chimney 4 communicates withexhaust gas outlet 9. Further, in the present embodiment, the system foroptimizing exhaust backpressure of an internal combustion engine mayalso include cooling water inlet pipe 16, cooling water outlet pipe 17,pump 18, control valve 19, heat exchanger 20, and heat utilizationapparatus 21, wherein cooling water inlet pipe 16, apparatus 5 foroptimizing exhaust backpressure of an internal combustion engine,cooling water drain pipe 17 constitutes a flow path of cooling water.Heat exchanger 20 is mounted on the cooling water drain pipe 17 fortransferring the heat of the cooling water having absorbed heat toanother fluid, and for further transferring to heat utilizationapparatus 21 for utilization.

The apparatus and system of the present embodiment is used by thefollowing method: when the ship is sailing in the ocean, the internalcombustion engine works to produce high-temperature exhaust gas(approximately 500° C. or so), which is discharged through exhaust pipeof the internal combustion engine and then enters the housing of theapparatus for optimizing exhaust backpressure of an internal combustionengine through exhaust gas inlet pipe; cooling water inlet pipe extractssea water directly from its immediate natural environment, and sea wateris conveyed into the housing of the apparatus for optimizing exhaustbackpressure of an internal combustion engine via pump. Under the effectof exhaust pressure and natural diffusion, exhaust gas flows by in theinterior of the housing from bottom to top; under the effect of gravity,sea water flows by in the interior of the housing from top to bottom.High-temperature exhaust gas is divided into small tributaries inpadding layer, and comes into contact with sea water to be quicklycooled. The cooled exhaust gas (approximately 30° C. to 80° C. afterpassing through padding layer) is discharged into the atmosphere throughthe chimney. Sea water having absorbed heat is drained from the coolingwater outlet, and then flows through the cooling water drain pipe totransfer heat to another fluid via heat exchanger, and then isdischarged into the ocean. Another fluid that has absorbed heat in theheat exchanger is conveyed to heat utilization apparatus to be utilized.

The above embodiment utilizes padding layer having large gaps to dividehigh-temperature exhaust gas into a plurality of small tributaries so asto provide certain amount of exhaust resistance and rapidly cool thehigh-temperature exhaust gas in padding layer. The cooledhigh-temperature exhaust gas has a sudden extraction in its volume andthe quantity and rate of flow thereof declined, and the resistancecaused thereby is decreased by a larger extent. The exhaust backpressureof the internal combustion engine is relatively lowered, so that notonly the working condition of ventilation of the internal combustionengine is improved, but also pressure boost efficiency of theturbocharger is enhanced. In the present embodiment, the exhaustbackpressure relatively decreases with the increase of the load, thuscompletely eliminating the factors sensitive to exhaust backpressure. Inaddition, as the present embodiment also provides a certain amount ofbackpressure when the internal combustion engine is under low load, thetorque of the internal combustion engine is thus increased.

In the present embodiment, apparatus 5 for optimizing exhaustbackpressure of an internal combustion engine also plays a role of amuffler. The principle of muffling pertains to the impedance compositemuffling, having both muffling characteristics of resistance andreactance. As the high-temperature exhaust gas of hundreds of degreesCelsius is cooled down to several tens of degrees Celsius, producing acooling expansion effect of simultaneously enhancing muffling effect ofresistance and reactance, thus a better muffling effect is obtained thanprior art.

A ton class vessel is installed with the system for optimizing exhaustbackpressure of an internal combustion engine provided by theembodiment. The main pushing diesel engine displacement thereof is P=336liters, combusting heavy oil with sulfur content of 2% to 3% mm.According to the spatial conditions along the path of the exhaustpassage of the internal combustion engine, the volume of the housing ofthe apparatus for optimizing exhaust backpressure of an internalcombustion engine is selected in the scope of 3-30 times of exhaustamount of the internal combustion engine. According to size of theexhaust gas intake pipe 3, cross-sectional area of the exhaust gasintake pipe is 0.3 m², and cross-section area of housing is selectedaccording to 0.05-0.5 time thereof, then the volume of the housing isselected as 5.3 m³, cross-sectional area selected as 1.8 m². Anapparatus for optimizing exhaust backpressure of an internal combustionengine is installed on the exhaust passage of the main pushing dieselinternal combustion engine, and the main pushing internal combustionengine of that ship is no longer configured with muffler and waste heatboiler.

The cooling water conveyed to the apparatus for optimizing exhaustbackpressure of an internal combustion engine is extracted from seawater by pump, the amount of cooling water being controlled to be 20-100m³/h.

Tested by the applicant, after the above vessel applied with thisembodiment, the exhaust noise of the vessel is reduced by 23 db.

FIG. 3 is a schematic diagram showing the relationship between theexhaust backpressure of the vessel and load rate of the internalcombustion engine that are tested by the applicant in the firstembodiment, wherein the data of the prior art is obtained by testing thevessel (other configuration are the same as the configuration of thevessel of the present embodiment) mounted with muffler and waste heatboiler. The exhaust backpressure data is collected from exhaust gasinlet, with unit of Pa. It can be seen from the result in the figurethat after installing the apparatus of the present invention, theexhaust backpressure of the present embodiment is a little larger thanthat of the prior apparatus (muffler) when the internal combustionengine is under low load. With the increase of the load of an internalcombustion engine, the exhaust backpressure of the prior art increasesrapidly, while the exhaust backpressure of the present embodimentincreases with a velocity and extent much smaller than that of the priorart.

FIG. 4 is a schematic diagram showing the relationship between exhaustgas temperature of the vessel and the load rate of the internalcombustion engine that are practically tested by the applicant in thefirst embodiment, wherein the data of the prior art is obtained bytesting the vessel (other configuration are the same as theconfiguration of the vessel of the present embodiment) mounted withmuffler and waste heat boiler. The data of temperature is collected atthe discharge port of the chimney. It can be seen from the result in thefigure that in a vessel of the prior art, the temperature of the exhaustgas discharged is increased with the increase of the load of an internalcombustion engine, maximum to about 350° C. Obviously, there is a lot ofwaste heat in the exhaust gas that is not utilized yet. While afterinstalling the apparatus of the present embodiment, the exhausttemperature has been stable at about 30° C.

FIG. 5 shows an apparatus for optimizing exhaust backpressure of aninternal combustion engine according to the second embodiment of thepresent invention.

In this embodiment, different from the apparatus for optimizing exhaustbackpressure of an internal combustion engine in the first embodiment,exhaust gas inlet 7 of the apparatus for optimizing exhaust backpressureof an internal combustion engine is located on the lower portion of theside surface of housing 6; in the direction of gravity, the position ofexhaust gas inlet 7 is higher than that of rinsing water outlet 11. Inthis case, the exhaust passage of the internal combustion enginecommunicates with the side surface of the housing through exhaust gasinlet 8. As the exhaust gas enters from the side surface of the housing,there is no need for a water baffle.

The exhaust passage of the internal combustion engine communicates withthe side surface of the housing of the apparatus for optimizing exhaustbackpressure of an internal combustion engine. In the presentembodiment, the displacement of the internal combustion engine is P=33liter, housing volume is 0.2 m³, cross-sectional area is 0.3 m²,cross-sectional area of exhaust gas intake pipe is 0.06 m².

FIG. 6 illustrates a system for optimizing exhaust backpressure of aninternal combustion engine according to the third embodiment of thepresent invention.

Different from the system for optimizing exhaust backpressure of aninternal combustion engine in the first embodiment, in this embodiment,the cooling water in the system for optimizing exhaust backpressure ofan internal combustion engine is taken from the cooling water of theinternal combustion engine, the cooling water which has absorbed heatcan be directed drained in the same way as the cooling water of theinternal combustion engine.

FIG. 7 illustrates a system for optimizing exhaust backpressure of aninternal combustion engine according to the forth embodiment of thepresent invention.

Different from the system for optimizing exhaust backpressure of aninternal combustion engine according to the first embodiment, in thisembodiment, the system for optimizing exhaust backpressure of aninternal combustion engine, in addition to including a pipe conveyingthe fluid of the housing to heat exchanger 20, also includes a pipeconveying the fluid of heat exchanger 20 to the housing.

In this kind of system for optimizing exhaust backpressure of aninternal combustion engine, the cooling water that has absorbed heatfrom high-temperature exhaust gas is conveyed to the housing to act ascooling water again after passing through heat exchanger 20, so as torealize recycling utilization.

Further, the system for optimizing exhaust backpressure of an internalcombustion engine in this embodiment also includes impurity separator 22installed in the cooling water drain pipe for filtering the impuritiesin the cooling water, discharging the impurities from impurity dischargepipe 24, so as to prevent particles brought by the cooling water fromaccumulating too much. Impurity separator 22 has the function of addingcooling water at the same time, supplementing through cooling watersupplementing pipe 23 the cooling water decreased due to evaporation.

FIG. 8 illustrates the apparatus for optimizing exhaust backpressure ofan internal combustion engine according to the fifth embodiment.

In this embodiment, heat dissipating member 25 is provided in thehousing of the apparatus for optimizing exhaust backpressure of aninternal combustion engine, i.e. cooling member. Heat dissipating member25 is composed of heat pipe 26, heat absorbing sheet 27 and heatdissipating sheet 28. Heat absorbing sheet 27 is located in the interiorof the housing, made of good heat conductor, for dividing the exhaustgas into small tributaries and absorbing the heat in the exhaust gas.Heat dissipating sheet 28 is located outside of the housing, made ofgood heat conductor, for releasing heat into the environment. Heat pipe26 connects heat absorbing sheet 27 and heat dissipating sheet 28, madeof good heat conductor, for transferring the heat absorbed by the heatabsorbing sheet to the heat dissipating sheet.

When the high-temperature exhaust gas discharged from the internalcombustion engine passes through the apparatus in this embodiment, it isdivided by heat absorbing sheet 27 into small tributaries, and is cooledat the same time through heat exchanging with heat dissipating member25.

The apparatus for optimizing exhaust backpressure of an internalcombustion engine in this embodiment may also be directly installed indevice using internal combustion engine as the power on the land, suchas automobiles.

FIG. 9 illustrates the apparatus for optimizing exhaust backpressure ofan internal combustion engine according to the sixth embodiment of thepresent invention.

Cooling pipe 29 allowing cooling water flowing therein is provided inthe housing of the apparatus for optimizing exhaust backpressure of aninternal combustion engine in this embodiment, i.e. cooling member.Cooling pipe 29 is densely distributed in the housing, and thus may actsto divide the exhaust gas into small tributaries.

In use, cooling water is kept flowing in the cooling pipe, and theexhaust gas is rapidly cooled during the process of being divided intosmall tributaries. The cooling water forms vapor after absorbing theheat from the high-temperature exhaust gas, and the vapor formed may beconveyed to heat utilization apparatus to be directly utilized.

The apparatus in this embodiment may be installed on the ship, thecooling water being taken from the sea water, river water or lake waterfrom a natural water body. Cooling water may also use the cooling waterof the internal combustion engine. The apparatus may also be installedin an automobile, and the cooling water may also use the cooling waterof the internal combustion engine.

FIG. 10 illustrates the apparatus for optimizing exhaust backpressure ofan internal combustion engine according to the seventh embodiment of thepresent invention.

The apparatus for optimizing exhaust backpressure of an internalcombustion engine in this embodiment includes housing 6 provided withexhaust gas inlet 7 and exhaust gas outlet 9. Different from above, noabrupt expansion of cross-sections is formed from exhaust gas inlet 7 tothe interior of the housing, wherein the existence of exhaust gas inlet9 reduces the cross-section of the exhaust passage so as to provide acertain amount of exhaust resistance.

The apparatus in this embodiment also includes sprayer 15, for sprayingcooling water to the interior of the housing, thereby rapidly reducingthe temperature of the high-temperature exhaust gas. The cooling waterwhich has absorbed heat is discharged from cooling water outlet 11.

What is claimed is:
 1. A method for optimizing exhaust backpressure ofan internal combustion engine, comprising: 1) providing a damping memberin an exhaust passage of an internal combustion engine, and makingexhaust gas discharged from said internal combustion engine passingthrough said damping member; 2) cooling the exhaust gas before passingthrough said damping member, or cooling the exhaust gas while passingthrough said damping member.
 2. A method as claimed in claim 1, whereinsaid damping member is a member able to reduce a cross-section of theexhaust passage.
 3. A method as claimed in claim 2, wherein said memberable to reduce a cross-section of the exhaust passage is an exhaust pipewith abruptly reduced cross-sections.
 4. A method as claimed in claim 2,wherein said member able to reduce a cross-section of the exhaustpassage is a member having pores disposed in the exhaust pipe.
 5. Amethod as claimed in claim 1, wherein said damping member is a memberthat is able to split the exhaust gas into a plurality of smalltributaries.
 6. A method as claimed in claim 1, wherein said dampingmember is an exhaust pipe able to change a flow direction of the exhaustgas.
 7. A method as claimed in claim 1, wherein a method of cooling theexhaust gas is: dividing the exhaust gas into a plurality of smalltributaries, and then making the scattered small tributaries exchangeheat with a cooling medium.
 8. A method as claimed in claim 1, wherein amethod of cooling the exhaust gas is: making the exhaust gas and acooling liquid come into contact with each other.
 9. A method as claimedin claim 1, wherein a method of cooling the exhaust gas is: making theexhaust gas pass through a member having a large number of gaps to bedivided into a plurality of small tributaries, and making said smalltributaries and a cooling liquid come into contact in said gaps.
 10. Amethod as claimed in claim 1, wherein said damping member is locatedwithin a housing, and the exhaust gas discharged from an internalcombustion engine is cooled within the housing, wherein said methodfurther comprises: making the exhaust gas discharged from the internalcombustion engine enter into an interior of said housing through aexhaust gas inlet of said housing, and then making the cooled exhaustgas discharge out of said housing through a exhaust gas outlet of saidhousing.
 11. A method as claimed in claim 10, wherein an abruptexpansion of cross-sections is formed from said exhaust gas inlet to theinterior of said housing.
 12. A method as claimed in claim 11, whereinthe cross-section area of said exhaust gas inlet is 0.05 to 0.5 timesthe cross-sectional area of said housing.
 13. A method as claimed inclaim 1, wherein a method of cooling the exhaust gas is: making theexhaust gas and a cooling liquid come into contact with each other in aninterior of a housing, wherein said method further comprises: making thecooling liquid enter into an interior of the housing through a coolingwater inlet of said housing, and discharging the cooling liquid havingabsorbed heat of the exhaust gas from the housing through a coolingwater outlet of said housing.
 14. A method as claimed in claim 13,wherein said cooling liquid is cooling water in natural water body,wherein said method further comprises: extracting cooling water fromnatural water body and conveying it to said housing.
 15. A method asclaimed in claim 13, wherein said cooling liquid is cooling water of aninternal combustion engine, wherein said method further comprises:conveying cooling water of an internal combustion engine to saidhousing.
 16. A method as claimed in claim 13, wherein said methodfurther comprises: conveying the cooling liquid having absorbed heat ofthe exhaust gas to a heat utilization apparatus or a heat exchanger. 17.A method as claimed in claim 1, wherein said method further comprises:the exhaust gas discharged from an internal combustion engine flowingthrough impellers of a turbocharger working prior to entering saidhousing.
 18. An apparatus for optimizing exhaust backpressure of aninternal combustion engine, comprising: 1) a housing; 2) a exhaust gasinlet provided on the housing allowing a exhaust gas to enter into aninterior of the housing, a exhaust gas outlet provided thereon allowinga exhaust gas to be discharged out of the housing; 3) a damping memberprovided in the interior of the housing or on the housing; 4) a coolingmember provided in the interior of the housing for cooling a exhaustgas.
 19. An apparatus as claimed in claim 18, wherein an abruptexpansion of cross-sections is formed from said exhaust gas inlet to theinterior of said housing.
 20. An apparatus as claimed in claim 19,wherein the cross-section area of said exhaust gas inlet is 0.05 to 0.5times the cross-sectional area of said housing.
 21. An apparatus asclaimed in claim 18, wherein said damping member is a padding layer ofpaddings filled in said housing with gaps therebetween.
 22. An apparatusfor optimizing exhaust backpressure of an internal combustion engine,comprising: 1) a housing; 2) a exhaust gas inlet provided on the housingallowing a exhaust gas to enter into an interior of the housing, aexhaust gas outlet provided thereon allowing a exhaust gas to bedischarged out of the housing; 3) a damping member provided in aninterior of the housing or on the housing; 4) a cooling water inletprovided on the housing allowing cooling water to enter into thehousing, a cooling water outlet provided thereon allowing cooling waterto be discharged out of the housing; said cooling water inlet, coolingwater outlet, exhaust gas inlet and exhaust gas outlet configured sothat cooling water and exhaust gas able to come in to contact with eachother in an interior of the housing.
 23. A system for optimizing exhaustbackpressure of an internal combustion engine, comprising an exhaustpassage of an internal combustion engine, wherein said system furthercomprises an apparatus for optimizing exhaust backpressure of aninternal combustion engine as claimed in claim 22, which is mounted insaid exhaust passage of an internal combustion engine.
 24. A system asclaimed in claim 23, further comprising an apparatus for allowingexhaust gas emission to generate pressure drop, mounted in said exhaustpassage of an internal combustion engine, and located downstream of saidapparatus for optimizing exhaust backpressure of an internal combustionengine.
 25. A system as claimed in claim 23, further comprising: anapparatus able to extract cooling water from natural water, and conveyit to said housing.
 26. A system as claimed in claim 23, furthercomprising: an apparatus able to convey cooling water of an internalcombustion engine to said housing.
 27. A system as claimed in claim 23,further comprising a heat utilization apparatus or heat exchanger, and apipe able to convey fluid from said housing to said heat utilizationapparatus or heat exchanger.
 28. A system as claimed in claim 23,further comprising a turbocharger, said exhaust passage of an internalcombustion engine is a exhaust gas passage connected to an exhaust portat the exhaust gas side of said turbocharger.
 29. A method for mufflingexhaust gas of an internal combustion engine, comprising: discharging ahigh-temperature exhaust gas from an internal combustion engine enteringinto an interior of a housing through a exhaust gas inlet on thehousing, and further comprising: allowing the high-temperature exhaustgas entering into an interior of the housing and a cooling liquid comeinto contact with each other.